This application is based upon and claims the benefits of priority from the prior Japanese Patent Application No. 2002-91672, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an optical fiber connector including optical fibers.
2. Description of the Related Art
FIG. 5 is a sectional view illustrating how an optical fiber connector 51 is connected to an optical component 61. The optical fiber connector 51 has a connector ferrule 53 and optical fibers 52 fixed in the connector ferrule. Guide pins 58 of the optical fiber connector 51 are inserted into respective guide holes (not shown) of the optical component 61, whereby the optical fiber connector 51 is connected to the optical component 61.
FIG. 6 is a longitudinal sectional view of the elements appearing in FIG. 5. As illustrated, each optical fiber 52 is fixed in the connector ferrule 53 of the optical fiber connector 51, and typically comprises two silica glass layers with different refractive indices, that is, a core 55 and a cladding 56 surrounding the core 55.
Typically, the dimensions of single-mode fibers commonly used are as follows: The core 55 has a diameter of 5 to 10 xcexcm, and the cladding 56 has an outer diameter of about 125 xcexcm.
On the connection end face, of the optical fiber connector 51, each optical fiber 52 protrudes from an end face of the connector ferrule 53 by about several micrometers.
On the other hand, the optical component 61 comprises, for example, an optical waveguide chip 69. Typically, the optical waveguide chip 69 has a structure wherein a cladding 66 corresponding to the claddings 56 of the optical fibers 52 is formed on a substrate 67 of silicon or the like and cores 65 corresponding to the respective cores 55 of the optical fibers 52 are embedded in the cladding 66. Each core 65 has a size of approximately 5 to 10 xcexcm in width as well as in height, and the cladding 66 has a height of about 50 xcexcm, for example.
As an exemplary part constituting the optical component 61, a top plate 68 of epoxy resin or the like is affixed to the optical waveguide chip 69 including the substrate 67, cores 65 and cladding 66 so that the optical component 61 may be connected to the optical fiber connector 51.
FIG. 7 is a sectional view exemplifying a state in which the optical fiber connector 51 is connected to the optical component 61. In the illustrated example, the optical component 61 has a connection end face 61a which is flat as a whole inclusive of the end faces of the substrate 67, cladding 66 and cores 65 of the optical waveguide chip and the end face of the top plate 68. Accordingly, the connection end faces 52a of the optical fibers 52 protruding from the connector ferrule in the optical fiber connector 51 can be brought into perfect connection, that is, desirable PC (Physical Contact), with the respective cores 65 of the optical waveguide chip 69.
FIG. 8 is a sectional view illustrating another example of connection between the optical fiber connector 51 and the optical component 61. In the example shown in FIG. 8, the optical component 61 has an uneven connection end face 61b, that is, the cores 65 and the cladding 66 are set back from the substrate 67 and the top plate 68. Such unevenness of the connection end face 61b is often caused during polishing of the end face of the optical component 61 due to difference in abrasion resistance among the layers constituting the optical component, or is caused in high-temperature environments due to difference in the coefficient of thermal expansion among the layers. Thus, in some cases, the cores 65 are set back from the substrate 67 or the top plate 68 by about 0.5 xcexcm, for example.
In such cases, the optical fibers 52 of the optical fiber connector 51 are obstructed by the most prominent part of the optical component 61, for example, the top plate 68 in the example of FIG. 8, and the cores 55 thereof fail to come into PC with the respective cores 65 of the optical waveguide chip 69, giving rise to a problem of, for example, increased connector insertion loss.
To solve the problem, a method may be employed in which the total thickness of the core 65 and cladding 66 of the optical waveguide chip 69 is made significantly greater than the diameter of the optical fiber 52 so that the optical fibers 52 protruding from the connection end face of the optical fiber connector 51 may not touch the substrate 67 or top plate 68 of the optical waveguide chip 69. However, this method is not preferred in view of costs and time required to manufacture the optical waveguide chips 69.
An object of the present invention is to provide an optical fiber connector which permits the cores of optical fibers thereof to be connected to an optical component without fail even in cases where the connection end face of the optical component, to which the optical fiber connector is connected, is uneven and a region thereof to which the optical fibers are connected is recessed.
To achieve the object, the present invention provides an optical fiber connector comprising a connector ferrule having an end face serving as a connection end face side of the optical fiber connector, and an optical fiber fixed in the connector ferrule and protruding from the end face of the connector ferrule, wherein a central portion of the optical fiber including a core thereof protrudes from a peripheral portion thereof.